From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by smtp.lore.kernel.org (Postfix) with ESMTP id B44D9C6FA99 for ; Fri, 10 Mar 2023 14:27:46 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S232279AbjCJO1p (ORCPT ); Fri, 10 Mar 2023 09:27:45 -0500 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:52672 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S232394AbjCJO1Y (ORCPT ); Fri, 10 Mar 2023 09:27:24 -0500 Received: from dfw.source.kernel.org (dfw.source.kernel.org [139.178.84.217]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 6DDD2E4866 for ; Fri, 10 Mar 2023 06:25:55 -0800 (PST) Received: from smtp.kernel.org (relay.kernel.org [52.25.139.140]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by dfw.source.kernel.org (Postfix) with ESMTPS id F303E61948 for ; Fri, 10 Mar 2023 14:25:54 +0000 (UTC) Received: by smtp.kernel.org (Postfix) with ESMTPSA id 0B810C433EF; Fri, 10 Mar 2023 14:25:53 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=linuxfoundation.org; s=korg; t=1678458354; bh=kOw/u3wIeqdv+OoSevnE29hqGZKMDuAimoAme+/2zQA=; h=From:To:Cc:Subject:Date:In-Reply-To:References:From; b=o2RLfzSlVUDk6Hbia6NqmrmGeStlC78SQsk77jNOlIaygYURFKy32FzOUpxvY0+gj gtJ1WyrAd9JtCwgbacXch9jlPuMmltteq9U1IV+vsbqm79lXbcsdclTydRtNYNQvqX cjGQy1P5hR11A2ebLk0lAXb0uqYxGYFLfq9Z3xIY= From: Greg Kroah-Hartman To: stable@vger.kernel.org Cc: Greg Kroah-Hartman , patches@lists.linux.dev, Yunke Cao , Ricardo Ribalda , Laurent Pinchart Subject: [PATCH 4.19 250/252] media: uvcvideo: Fix race condition with usb_kill_urb Date: Fri, 10 Mar 2023 14:40:20 +0100 Message-Id: <20230310133727.199298643@linuxfoundation.org> X-Mailer: git-send-email 2.39.2 In-Reply-To: <20230310133718.803482157@linuxfoundation.org> References: <20230310133718.803482157@linuxfoundation.org> User-Agent: quilt/0.67 MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8bit Precedence: bulk List-ID: X-Mailing-List: stable@vger.kernel.org From: Ricardo Ribalda commit 619d9b710cf06f7a00a17120ca92333684ac45a8 upstream. usb_kill_urb warranties that all the handlers are finished when it returns, but does not protect against threads that might be handling asynchronously the urb. For UVC, the function uvc_ctrl_status_event_async() takes care of control changes asynchronously. If the code is executed in the following order: CPU 0 CPU 1 ===== ===== uvc_status_complete() uvc_status_stop() uvc_ctrl_status_event_work() uvc_status_start() -> FAIL Then uvc_status_start will keep failing and this error will be shown: <4>[ 5.540139] URB 0000000000000000 submitted while active drivers/usb/core/urb.c:378 usb_submit_urb+0x4c3/0x528 Let's improve the current situation, by not re-submiting the urb if we are stopping the status event. Also process the queued work (if any) during stop. CPU 0 CPU 1 ===== ===== uvc_status_complete() uvc_status_stop() uvc_status_start() uvc_ctrl_status_event_work() -> FAIL Hopefully, with the usb layer protection this should be enough to cover all the cases. Cc: stable@vger.kernel.org Fixes: e5225c820c05 ("media: uvcvideo: Send a control event when a Control Change interrupt arrives") Reviewed-by: Yunke Cao Signed-off-by: Ricardo Ribalda Reviewed-by: Laurent Pinchart Signed-off-by: Laurent Pinchart Signed-off-by: Greg Kroah-Hartman --- drivers/media/usb/uvc/uvc_ctrl.c | 5 +++++ drivers/media/usb/uvc/uvc_status.c | 37 +++++++++++++++++++++++++++++++++++++ drivers/media/usb/uvc/uvcvideo.h | 1 + 3 files changed, 43 insertions(+) --- a/drivers/media/usb/uvc/uvc_ctrl.c +++ b/drivers/media/usb/uvc/uvc_ctrl.c @@ -11,6 +11,7 @@ * */ +#include #include #include #include @@ -1323,6 +1324,10 @@ static void uvc_ctrl_status_event_work(s uvc_ctrl_status_event(w->chain, w->ctrl, w->data); + /* The barrier is needed to synchronize with uvc_status_stop(). */ + if (smp_load_acquire(&dev->flush_status)) + return; + /* Resubmit the URB. */ w->urb->interval = dev->int_ep->desc.bInterval; ret = usb_submit_urb(w->urb, GFP_KERNEL); --- a/drivers/media/usb/uvc/uvc_status.c +++ b/drivers/media/usb/uvc/uvc_status.c @@ -11,6 +11,7 @@ * */ +#include #include #include #include @@ -315,5 +316,41 @@ int uvc_status_start(struct uvc_device * void uvc_status_stop(struct uvc_device *dev) { + struct uvc_ctrl_work *w = &dev->async_ctrl; + + /* + * Prevent the asynchronous control handler from requeing the URB. The + * barrier is needed so the flush_status change is visible to other + * CPUs running the asynchronous handler before usb_kill_urb() is + * called below. + */ + smp_store_release(&dev->flush_status, true); + + /* + * Cancel any pending asynchronous work. If any status event was queued, + * process it synchronously. + */ + if (cancel_work_sync(&w->work)) + uvc_ctrl_status_event(w->chain, w->ctrl, w->data); + + /* Kill the urb. */ usb_kill_urb(dev->int_urb); + + /* + * The URB completion handler may have queued asynchronous work. This + * won't resubmit the URB as flush_status is set, but it needs to be + * cancelled before returning or it could then race with a future + * uvc_status_start() call. + */ + if (cancel_work_sync(&w->work)) + uvc_ctrl_status_event(w->chain, w->ctrl, w->data); + + /* + * From this point, there are no events on the queue and the status URB + * is dead. No events will be queued until uvc_status_start() is called. + * The barrier is needed to make sure that flush_status is visible to + * uvc_ctrl_status_event_work() when uvc_status_start() will be called + * again. + */ + smp_store_release(&dev->flush_status, false); } --- a/drivers/media/usb/uvc/uvcvideo.h +++ b/drivers/media/usb/uvc/uvcvideo.h @@ -603,6 +603,7 @@ struct uvc_device { /* Status Interrupt Endpoint */ struct usb_host_endpoint *int_ep; struct urb *int_urb; + bool flush_status; u8 *status; struct input_dev *input; char input_phys[64];